900,000+ datasheet pdf search and download

Datasheet4U offers most rated semiconductors data sheet pdf




Motorola Electronic Components Datasheet

MC12061 Datasheet

(MC12060 / MC12061) Crystal Switching Methods

No Preview Available !

www.DataSheet4U.com
CRYSTAL
MC1206[
@
MOTOROLA
‘Semiconductor
products
.. ~
gnc.


Motorola Electronic Components Datasheet

MC12061 Datasheet

(MC12060 / MC12061) Crystal Switching Methods

No Preview Available !

,, ..- ,.
www.DataSheet4U.com
,:”
.,.,:
cRYsTAL SWITCHINGMETHODs FOR
MCI 2060/MC12061OSCILLATORS
INTRODUCTION ‘
is dso an economical dual diode in the configuration
Crystal switching can be achieved electronically for the
needed for tfis circuit.
MC12060 and MC 12061 crystal oscillator integrated cir-
The MPN3401 is used with the MC 12061 circuit be-
cuits by utilizing diodes as RF switches. The switching is
controlled by applying a forward bias to the diode associ-
ated with the desired crystal and applying a reverse bias
to the remaining diodes, related to the unselected crystals.
in addition to functioning with the MC 12060/
MC 12061 IC’S, the switching circuit designs described .,
cause it offers a large off-to-on impedance ratio for low dc
bias currents at frequencies
MC12061.
DC BIAS REQUIREMENTS
within the range of the
.,i$.j..,,.,.l$!.$..,t}J,b:\;,,2k,\.‘*~,*:+,!*,~\{.>1?,~,,3$.,’,~~
~orward bias for ,the. ,desired cryst~=~$~~yti:g diode
here can dso be used’ in other applications where it i: ‘, ~~, (Dl ,’ D2; .D3Y D4, or .D5) is applie~,~b~~~~ing the five
desired to electronically switch series-resonant crystals ~ ‘
with a minimum of frequency pulling.
.
‘position switch. The’ bias current !i<s#<~,‘~~\r:,*,#.\~t\,y.mw set. by R17
and R2 (R4, R6, R&,’and R1.Oh$*~$efl<: t@~entlcal functions to
Advantages to this switchitig scheme include the following: ‘ ~‘, R2 when fiey are switched~in}~Th~fiur remaining sets of
1. Eliminates the need to run high frequency signals
through a mechanicrd switch;
2. Permits switching crystals from a remote position
with a minimum of disturbance to the oscillator;
bias “resistors, correspondi~$~$ the unselected crystals,
add a smaller arnoun~$~t, hkrent to the forward-biased
~,,<$”
diode. The total for~$d~$i~s current, ID, can be describ-
ed by the formulas’Y~~~~.at.i.?
3. Minimizes RF radiation;
‘,$:$~22v
4. Adapts easily to electronic scanning methods;
ID= ‘:’’sS~’::”R3+ R4 t R19 - (~)
5. Operates from a sin~e polarity, low voltage sUPPIY ,
(5.0 volts).
R2 +~]{,~;,t~%:,;~t‘->.(,,.[J,J]
.* *~...?,+.,..,.
4
)}
*<-$.
V-VD
GENERAL
IQ’-’’*>(,
“: “’$~lR~+{R~711 (R3+ ‘~R13)}
- (~)
The MC 12060 and MC 12061 crystal oscillators are :J&~$i$~
(For MCI 2060);
(For MC1206 ‘1) .
specified for operating frequency ranges of 100 kHz to $y~~~~~$
2.O MHz, and
outputs consist
2.0
of
MHz to 20 MHz respectively.
a sin~e-ended TTL signal, plus
,T,$hpemir’-.~’ “~>‘ti’:$. ure
While one
1) is always
diode (or one diode pair in the
forward biased, the remaining
case of Fig-
diodes are
: elementary sine wave tid ‘“ECL si~ds. The sim~~~~$~~ .,
reverse biased to minimize their capacitance. This is
outputs are capable of driving an ac load of ~@#* at
accomplished with a single polarity supply by using pullup
500 mVp-p (typical) when an external re~~~~Y~@used ~
resistors (R12, R13, R14, RI 5, and R16) from the posi-
to increase the current in the emitter f~~~f” output.
tive potential to each switch terminal. Therefore, the
The ECL and TTL outputs are capabl~:$~~~ting five and ~ cathodes of the diodes corresponding to the unselected
ten gate loads respectively.
..*.T\ !c\,,:,11.
crystals are pulled up to approximately the supply volt-
Series resonant crystals conne#ed~&#$ween pins 5 and
age. Since one diode (or diode pair) is always selected,
6 are required for use with~#~~$,#scfilatorsl The tot~ ““
current is flowing through R 17 continuously, causing a
effective ac series resistan~;,,~.,‘\{\.>,.~*~,.,~<talseries resonance re-
voltage drop. Therefore, the anodes of the unselected
sistance plus any addi@n~as&i>,:$.resistance contributed by
switching compone,~&)$ be~een these pins must “be less
diodes will be negative with respect to their cathodes.
When using a 5.0 volt supply, this reverse bias will be 1.6
than 4 k ohs for$~~3~~# 12060, and less than 155 ohms
volts for the MC 12060 and 1.2 volts for the MC 12061
for the MC 120@:~~.,#;i”$
c~stal switching array.
For additi~>@formation on these IC’S, see the device
data she$ki;&~AEfigineering Bulletins EB-58 and EB-59.
ADDITIONAL CONSIDERATIONS
Sch~at$+ ‘“diagrams for the MC 12060 and MC 12061
A sufficient amount of forward current through the
cryg{~$~~ltching circuits are given in Figures 1 and 2
diode selectirig the desired crystal is required to insure
~~~~~tively. The same basic technique is employed
a low value for diode resistance KD (see Figure 3). This is
f~~each IC except that an addifiond diode-resistor pair
important for two reasons:
(D6, R18 through D1O, R22) is incorporated for the
1. To minimize the effects of diode capacity on the
MC 12060 to offset its greater sensitivity to ac loading.
crystal’s natural series-resonant frequency.
The MPN3401 PIN diode and the MSD7000 PN junc-
2. To minimize the totrd effective external resistance
tion diode are used to switch the crystals. The MSD7000
between pins 5 and 6 of the integrated circuit.
was selected for use with the ‘MC12060 oscillator because
of its low capacitance (1.5 pF max. for VR = O volts). It
From Figure 3 it is apparent that as RD is made smal-
ler, Xs is decreased and Cs is increased. A large value for
Circuit diagrams external to Motorola products are included as a means of illustrating typical semiconductor
applications; consequently,
completa information sufficient for construction purposes is not necessarily givan. The information in this Application Note has been care-
fully checked and is believed to be antirely reliabla. However, no responsibility is assumed for inaccuracies. Furthermore, such information
doss not convey so the purchaser of:the semiconductor devices describad any. Iicanse. undar tha patent, righ= of Motorola Inc.b;.others.


Part Number MC12061
Description (MC12060 / MC12061) Crystal Switching Methods
Maker Motorola
PDF Download

MC12061 Datasheet PDF






Similar Datasheet

1 MC1206 THICK FILM CHIP RESISTOR
RCD
2 MC1206 Multilayer SMD Ceramic Capacitors
Multicomp
3 MC12060 (MC12x6x) MTTL
ETC
4 MC12060 (MC12060 / MC12061) Crystal Switching Methods
Motorola
5 MC12060 (MC12060 / MC12061) Crystal Oscillator
Motorola Semiconductor
6 MC12061 CRYSTAL OSCILLATOR
Motorola
7 MC12061 (MC12x6x) MTTL
ETC
8 MC12061 (MC12060 / MC12061) Crystal Switching Methods
Motorola
9 MC12061 (MC12060 / MC12061) Crystal Oscillator
Motorola Semiconductor





Part Number Start With

0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O    P    Q    R    S    T    U    V    W    X    Y    Z



Site map

Webmaste! click here

Contact us

Buy Components

Privacy Policy